A circuit technique substantially reduces the switching losses in an AC-DC power conversion system caused by turn-on characteristics of a main switch and the reverse-recovery characteristic of a rectifier. The losses are reduced by using an active soft-switching cell having a series inductor, a series capacitor, a main switch, a rectifier switch, and an auxiliary switch. The reverse-recovery related losses are reduced by the series inductor connected between the main and rectifier switches to control the rate of current change in the body diode of the rectifier switch during its turn-off. The main switch, the rectifier switch, and the auxiliary switch operate under zero-voltage switching (ZVS) conditions.

A switching converter includes: a reactor having one end to be connected to an AC power source; and a rectifier circuit connected to an opposite end of the reactor, the rectifier circuit converting a power source voltage applied by the AC power source into a DC voltage. The rectifier circuit includes a first leg and a second leg connected in parallel to the first leg. The first leg includes a first upper-arm element and a first lower-arm element connected in series. The second leg includes a second upper-arm element and a second lower-arm element connected in series. A snubber circuit including a resistor and a capacitor is connected to each of upper and lower-arm elements in one of the first and second legs. No snubber circuit is connected to upper and lower-arm elements in another of the first and second legs.

An embodiment method for controlling a power factor correction circuit includes detecting an AC zero voltage crossing point, detecting a current flowing through an inductor, and reducing a distortion of the current flowing through the inductor by determining a current at the AC zero voltage crossing point as a resistive current, an inductive current, or a capacitive current and controlling each of a plurality of switching elements from a time point when the AC zero voltage crossing point is detected based upon a result of determining the current.

In one example, a controller circuit is configured to: receive a first measurement signal representing a power converter input voltage; receive a second measurement signal representing a power converter output voltage; receive an indication of whether a voltage across a switch is positive during a state change of the switch; based on the first and second measurement signals and the indication, determine: a charging interval; a first dead time interval after the charging interval; a discharging interval; and a second dead time interval after the discharging interval; and provide a first control signal at the first control output, and provide a second control signal at the second control output, in which the states of the first and second control signals vary across the charging interval, the first and second dead time intervals, and the discharging the interval.

A power supply includes an inverter configured to direct current (DC) power into alternating current (AC) power, an impedance matching circuit configured to supply the AC power to a load; and a controller configured to adjust disposition of a powering period, in which the AC power is output, and a freewheeling period, in which the AC power is not output, to adjust a power amount of the power supplied to the load through the impedance matching circuit by the inverter.

A three-phase converter and a control method thereof are provided. The three-phase converter includes an AC terminal, three filter circuits, three bridge arm circuits, a capacitor module and a DC terminal connected in sequence and a controller. The midpoints of the filter circuits are connected to the midpoint of the capacitor module. The controller controls each bridge arm circuit to work in the first and second modes at different time in one line voltage cycle of the AC source. In the first mode, the bridge arm circuit works in a clamping state. In the second mode, the bridge arm circuit selectively works in a DCM mode or a TCM mode. A switching frequency is limited to be lower than a preset frequency. When the three-phase converter works with over 80% of a rated load, a time length of working in the second mode is ⅓˜⅔ of the line voltage cycle.

A dual active bridge includes a first converter arranged on a primary side of the dual active bridge, a second converter arranged on a secondary side of the dual active bridge, a high frequency transformer that has two windings and that operatively connects the first converter to the second converter, and a plurality of inductors, which are arranged along the legs on one of the two windings of the high frequency transformer, and which are split between the legs of that winding. In one embodiment, the plurality of inductors are split between the legs of the winding disposed on the secondary side of the dual active bridge. The plurality of inductors may consist of two inductors, of which a first one is arranged of the first leg of the winding and a second one is arranged on the second leg of the winding.

A single-phase and three-phase compatible conversion circuit includes an EMC module, a PFC module, a switch K1 and a control module. The EMC module is connected between lines A, B, C and N of a power grid and the PFC module. Three lines A1, B1 and C1 are led out from the EMC module and are connected with the PFC module, and are respectively connected to a set virtual midpoint through capacitors CX1, CX2, and CX3. The virtual midpoint is connected to a bus midpoint of the PFC module through the switch K1. The control module is used for detecting a power grid input signal and controlling the state of the switch K1 according to the type of the power grid input signal. The common-mode noise of the three-phase conversion mode can be reduced, and the three-phase conversion mode can be controlled within a larger bus voltage regulation range.

Technologies for controlling AC-to-DC converters are disclosed. In one illustrative embodiment, a controller of an AC-to-DC converter measures two voltage levels of a split voltage bus of a power factor correction (PFC) circuit. The controller controls current drawn from the positive and negative terminals of the PFC circuit by a DC-to-DC converter. By controlling the current drawn from the two terminals, the controller can control the voltages on the terminals to be equal (but opposite).

A totem pole PFC (Power Factor Correction) circuit, having: a first switch, a second switch and a control circuit. When the totem pole PFC circuit works in CCM (Continuous Current Mode), the control circuit is configured to turn on a main switch when a current detecting signal indicative of an AC input current of the totem pole PFC circuit decreases to a current valley reference signal, and keep the main switch ON for a first on-time period. When the totem pole PFC circuit works in DCM (Discontinuous Current Mode), the control circuit is configured to turn on the main switch at a valley of a switching voltage after expiry of a time delay started from when the AC input current decreases to zero, and keep the main switch ON for a second on-time period.